1. Field of the Invention
The present invention relates to a diffraction optical element, a molding die for the diffraction optical element and a manufacturing method of the molding die.
2. Description of the Related Art
Recently, with enhanced requirement for high performance and miniaturization in optical systems, a diffraction optical element has been getting people's attention. More particularly, a diffraction optical element whose diffraction gratings have a blazed profile (i.e. saw-tooth appearance) in section is frequently utilized in an optical system of an optical equipment since such a diffraction optical element is low in profile and high in diffraction efficiency.
Japanese Patent Publication Laid-open No. 2002-189114 discloses a method of manufacturing such a diffraction optical element. In accordance with the disclosed manufacturing method, the diffraction optical element is produced by using plastic material and a molding die in which a number of inverse-shaped grooves are formed to have an inverse profile to the diffraction gratings by cutting operation.